part4custom: add E06 (ValueDeserializer direct) and E07 (mix-in on a record), fix run-all.sh exit-code detection through the grep filter (post #50)

src/main/java/com/ankurm/jackson3/part4custom/E06ValueDeserializerDirect.java

@@ -0,0 +1,65 @@
+package com.ankurm.jackson3.part4custom;
+
+import tools.jackson.core.JsonParser;
+import tools.jackson.databind.DeserializationContext;
+import tools.jackson.databind.ValueDeserializer;
+import tools.jackson.databind.json.JsonMapper;
+import tools.jackson.databind.module.SimpleModule;
+
+/**
+ * BEYOND THE POST — the deserialising half of E05ValueSerializerDirect.
+ *
+ * E05 showed ValueSerializer<T> written directly, without the StdSerializer detour.
+ * This is the other half: ValueDeserializer<T> written directly, without StdDeserializer.
+ * Together they round-trip UserId as a bare JSON string ("u-42") instead of the
+ * structural {"value":"u-42"} a record would otherwise produce.
+ */
+public class E06ValueDeserializerDirect {
+
+    public record UserId(String value) { }
+
+    static class UserIdSerializer extends tools.jackson.databind.ValueSerializer<UserId> {
+        @Override
+        public void serialize(UserId id, tools.jackson.core.JsonGenerator gen,
+                               tools.jackson.databind.SerializationContext ctxt) {
+            gen.writeString(id.value());
+        }
+    }
+
+    /** Reads the bare JSON string straight back into the wrapper type. */
+    static class UserIdDeserializer extends ValueDeserializer<UserId> {
+        @Override
+        public UserId deserialize(JsonParser p, DeserializationContext ctxt) {
+            return new UserId(p.getString());
+        }
+    }
+
+    public record Ticket(UserId assignee, String title) { }
+
+    public static void main(String[] args) {
+        SimpleModule module = new SimpleModule("UserIdModule");
+        module.addSerializer(UserId.class, new UserIdSerializer());
+        module.addDeserializer(UserId.class, new UserIdDeserializer());
+
+        JsonMapper mapper = JsonMapper.builder().addModule(module).build();
+
+        Ticket original = new Ticket(new UserId("u-42"), "Fix build");
+        String json = mapper.writeValueAsString(original);
+        System.out.println("serialised : " + json);
+
+        Ticket restored = mapper.readValue(json, Ticket.class);
+        System.out.println("round-trip : " + restored);
+        System.out.println("equal      : " + original.equals(restored));
+
+        // Without the module, Jackson can't turn a bare JSON string "u-42" into a
+        // one-component record - it expects {"value":"u-42"} and this throws.
+        JsonMapper plain = JsonMapper.builder().build();
+        try {
+            plain.readValue("{\"assignee\":\"u-42\",\"title\":\"Fix build\"}", Ticket.class);
+            System.out.println("no module  : (unexpectedly succeeded)");
+        } catch (Exception e) {
+            System.out.println("no module  : " + e.getClass().getSimpleName()
+                    + " - " + e.getMessage().lines().findFirst().orElse(""));
+        }
+    }
+}

src/main/java/com/ankurm/jackson3/part4custom/E07MixinOnRecord.java

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+package com.ankurm.jackson3.part4custom;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import tools.jackson.databind.json.JsonMapper;
+
+/**
+ * BEYOND THE POST — does addMixIn() still work when the third-party type is a
+ * record, not a field-and-getter class like E04's Address?
+ *
+ * A record's "properties" are its canonical accessor methods (postalCode(), not
+ * getPostalCode()), so a mixin has to declare methods with those exact names for
+ * Jackson's annotation-introspection merge to find them. Run this before assuming
+ * either way - the answer below was obtained by actually running it, not inferred
+ * from how E04's field-based mixin behaves.
+ */
+public class E07MixinOnRecord {
+
+    /** Stand-in for a third-party record type whose source you cannot modify. */
+    public record AddressRecord(String street, String city, String postalCode,
+                                 String internalTrackingCode) { }
+
+    /** Mix-in for AddressRecord: method signatures, not fields, to match a record's accessors. */
+    public interface AddressRecordMixin {
+        @JsonIgnore
+        String internalTrackingCode();
+
+        @JsonProperty("zip")
+        String postalCode();
+    }
+
+    public static void main(String[] args) {
+        AddressRecord address = new AddressRecord(
+                "123 Main St", "Springfield", "12345", "INTERNAL-X99");
+
+        JsonMapper withMixin = JsonMapper.builder()
+                .addMixIn(AddressRecord.class, AddressRecordMixin.class)
+                .build();
+        System.out.println("with mixin   : " + withMixin.writeValueAsString(address));
+
+        JsonMapper withoutMixin = JsonMapper.builder().build();
+        System.out.println("without mixin: " + withoutMixin.writeValueAsString(address));
+    }
+}